Shield for high-frequency transmitter/receiver systems of electronic devices, especially of devices for wireless telecommunication

ABSTRACT

The invention relates to a shield for high-frequency transmitter/receiver systems of electronic devices, especially of devices for wireless telecommunication. In order to reduce the space requirements of such a high-frequency transmitter/receiver system ( 2 ′) on a circuit support element ( 1 ′) of an electronic device, a first partial circuit ( 20 ′) of the high-frequency transmitter/receiver system ( 2 ′) and a second partial circuit ( 21 ′) of the high-frequency transmitter/receiver system ( 2 ′) are disposed in a single shield chamber ( 32 ) in a substantially separate especially locally/partially separate manner. The shield chamber ( 32 ) is linked with a grounded area ( 10 ′) on the support element ( 1 ′) via an electroconducting connection ( 320 ) and the connecting element ( 320 ) is interposed between the two partial circuits ( 20′, 21 ′) on the support element ( 1 ′) in such a way that the twp partial circuits ( 20′, 21 ′) on the support element ( 1 ′) in such a way that the two partial ( 20′, 21 ′) do not interfere with each other functionally.

BACKGROUND OF THE INVENTION

Electronic wireless telecommunications devices such as cordlesstelephones based on the DECT standard (Digital Enhanced CordlessTelecommunication) or mobile telephone handsets based on the GSMstandard (Groupe Spéciale Mobile or Global System for MobileTelecommunication) not only have circuits for signal processing in thelow-frequency baseband but also have radio-frequency transceivers. Thesecircuits and RF devices are usually mounted on a substrate, theso-called circuit board, in numerous process engineering and componentinsertion operations. In the course of electronic deviceminiaturization, films rather than circuit boards are increasingly beingused as substrates.

FIG. 1 shows, from known prior art, a substrate 1 with a ground plane 10on which there is disposed a radio-frequency transceiver 2 connected toa wire antenna 3, which is likewise disposed on the substrate 1. Theradio-frequency transceiver 2 contains two sub-circuits 20, 21; a firstsub-circuit 20 having, for example, an output power amplifier 200, and asecond sub-circuit 21 having, for example, oscillators 210 andsynthesizers 211. The two sub-circuits 20, 21, in a certain spatialarrangement, tend to produce mutual interference in respect of the RFfields but must not interfere with one another in terms of theirrespective functions. Radiated interference and interference from theenvironment likewise must be prevented. This scenario is schematicallyindicated in FIG. 1 by the arrows. The double-headed horizontal andvertical arrows indicate the electromagnetic fields emitted by thesub-circuits 20, 21 which affect the sub-circuits 20, 21. Thethree-dimensionally represented arrow indicates the phenomenon ofcrosstalk from the first sub-circuit 20 to the second sub-circuit 21,and vice versa. The remaining arrows indicate the presence of balancingcurrents in the substrate 1 and shielding chambers. In other words, thedevice must satisfy the requirements of internal and externalelectromagnetic compatibility (EMC).

To achieve this, the sub-circuits 20, 21 of the radio-frequencytransceiver 2 on the substrate 1 are enclosed by at least two shieldingchambers 30, 31 in such a way that the individual sub-circuits arecompletely shielded (i.e.,, RF-proof), a first shielding chamber 30being used as self-contained shielding for the first sub-circuit 20,while a second shielding chamber 31 is used exclusively as shielding forthe second sub-circuit 21. In accordance with this prior art, there areprovided between the sub-circuits 20, 21 two continuous isolationbarriers which prevent interference effects.

An object of the present invention is to reduce the space requirementfor the shielding of the radio-frequency transceiver on a circuitsubstrate of an electronic device, particularly of wirelesstelecommunications equipment.

SUMMARY OF THE INVENTION

The idea underlying the present invention is that there are disposed ona circuit substrate of an electronic device, under a single shieldingchamber, a first sub-circuit of a radio-frequency transceiver and asecond sub-circuit of the radio-frequency transceiver which aresubstantially (in particular, locally/spatially separate from oneanother. The shielding chamber is connected to a ground plane on thesubstrate via an electrically conductive connecting element and theconducting element is disposed between the two sub-circuits on thesubstrate in such a way that the two sub-circuits do not interferefunctionally with one another.

Because of the space saved on the circuit substrate by not having asecond shielding chamber, it is possible, for example, to implementsmaller electronic devices with radio-frequency transceivers than everbefore. For electronic devices for wireless telecommunications, thisresults in such devices being able to be incorporated, for example, in awristwatch.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view of the structure of a radiofrequency transceiver on a substrate with two shielding chambers asknown in the prior art.

FIG. 2 based on FIG. 1 is a schematic perspective view of the structureof a radio-frequency transceiver on a substrate with a single shieldingchamber in accordance with the present invention.

FIG. 3 is a cross-sectional view of FIG. 2 along the line A . . . A′.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 shows a substrate 1′ with a ground plane 10′ on which there isdisposed a radio-frequency transceiver 2′ which is connected to a wireantenna 3′, likewise disposed on the substrate 1′. The radio-frequencytransceiver 2′ contains two sub-circuits 20′, 21′; a first sub-circuit20′ having, for example, an output power amplifier 200′, and a secondsub-circuit 21′ having, for example, oscillators 210′ and synthesizers211′. The two sub-circuits 20, 21, in a certain spatial/localarrangement, tend to produce mutual interference in respect of the RFfields but must not interfere with one another in terms of theirrespective functions. Radiated interference and interference from theenvironment likewise must be prevented. This scenario is againschematically indicated in FIG. 1 by the arrows. The double-headedvertical arrows indicate the electromagnetic fields emitted by thesub-circuits 20′, 21′ which affect the sub-circuits 20′, 21′. Thethree-dimensionally represented arrow indicates the phenomenon ofcrosstalk from the first sub-circuit 20′ to the second sub-circuit 21′,and vice versa. The remaining arrows as per FIG. 3 indicate the presenceof balancing currents in the substrate 1′ and shielding chambers. Inother words, the device must satisfy the requirements of internal andexternal electromagnetic compatibility (EMC).

To achieve this, the sub-circuits 20′, 21′ of the radio-frequencytransceiver 2′ on the substrate 1′ are, in contrast to the approach inFIG. 1, enclosed by a single shielding chamber 32 in such a way that theindividual sub-circuits are completely shielded; i.e., so to speak,RF-proof. As the two sub-circuits 20′, 21′ are both completely enclosedby the shielding chamber, with no continuous isolation barrier beingpresent between the sub-circuits 20′, 21′ in the prior art asillustrated in FIG. 1, mutual interference between the sub-circuits 20′,21′ is prevented; particularly, the abovementioned crosstalk. Theshielding chamber 32 must be further developed and/or the disposition ofthe sub-circuits under the shielding chamber must be optimized so as toensure that this interference does not occur or is at least largelysuppressed.

For this purpose, the shielding chamber 32 as shown in FIGS. 2 and 3 isconnected to an electrically conductive connecting element 320 whichpreferably is a component, a spring or a dome-like structure made of thesame material (preferably, nickel silver), as the shielding chamber 32.On the opposite side, this connecting element 320 is connected to theground plane 10′ on the substrate 1′, thereby establishing an electricalconnection from the cover of the shielding chamber 320 to the groundplane 10′. Currents required for the output power amplifier 200′ arederived via this connection (tapping). The currents of the output poweramplifier 200′ are kept away from the oscillators 210′ and synthesizers211′ via this connection.

To achieve this, the connecting element 320 is disposed between the twomutually interfering sub-circuits 20′, 21′ on the substrate 1′ in such away that the two sub-circuits 20′, 21′ do no interfere with one anotherfunctionally. Disposed in this way, substantially the same shieldingeffect can be achieved with the connecting element 320 as with at leastone isolation barrier according to the prior art. The connecting element320, therefore, constitutes a fictitious isolation barrier for the twosub-circuits 20′, 21′, provided that these are substantially disposed(in particular, locally/spatially) separate from one another on thesubstrate 1′ under the shielding chamber 320.

Thus, in spite of the fictitious isolation barrier, the sub-circuits20′, 21′ preferably should not be immediately adjacent or adjoining, asshown schematically in FIG. 3.

Although the present invention has been described with reference tospecific embodiments, those of skill in the art will recognize thatchanges may be made thereto without departing from the spirit and scopeof the present invention as set forth in the hereafter appended claims.

1. Shielding for radio-frequency transceivers of electronic devices,particularly of wireless telecommunications devices, having thefollowing features: (a) On a circuit substrate (1′) of the electronicdevice there are disposed under a single shielding chamber (32) a firstsub-circuit (20′) of the radio-frequency transceiver (2′) and a secondsub-circuit (21′) of the radio-frequency transceiver (2′) essentiallyseparated from one another, in particular locally/spatially separated,(b) the shielding chamber (32) is connected on the substrate (1′) to aground plane (10′) via an electrically conductive connecting element(320), (c) the connecting element (320) is disposed between the twosub-circuits (20′, 21′) on the substrate (1′) in such a way that the twosub-circuits (20′, 21′) do not interfere with one another functionally.2. Shielding according to claim 1, wherein the connecting element (320)is an electrical component which can be inserted with the components ofthe sub-circuits (20′, 21′) on the substrate (1′).
 3. Shieldingaccording to claim 1, wherein the connecting element (320) is a spring.4. Shielding according to claim 1, wherein the connecting element (320)is a dome-like structure.
 5. Shielding according to claim 1 or 4,wherein the connecting element (320) and the shielding chamber (32) aremade of the same material.
 6. Shielding according to claim 5, whereinthe material is low-impedance.
 7. Shielding according to claim 5 or 6,wherein the material is nickel silver.